Conventional digital signal processing systems include a digital signal processor (DSP) and memory modules matched to the speed performance of the DSP. The performance of a high speed DSP system is often limited by the speed of available or affordable memory modules. Available or affordable memory access time is often slower than that of the DSP addressing cycle, thereby setting the maximum speed of the DSP system at the maximum speed of the memory modules. This wastes available processing time (and thereby much of the power) of the DSP.
Conventional high speed memory modules are also very expensive and consume large amounts of electrical power. Often times memory modules are not commercially available to suit the needs of high speed digital signal processing systems.
The conventional DSP system contains a DSP with a single address and data bus and an appropriately sized memory module accessed directly over the DSP address and data bus. Since often times the speed of the memory is the limiting performance factor of a digital signal processing system, the DSP must typically be "held" in place during a memory access until the memory "catches up". This is lost processing time resulting in reduced performance of the DSP system.
For instance, in a system in which a DSP has a 20 nano-second memory access cycle, but the memory is much slower, having a 100 nano-second access time, the DSP memory access cycle must be delayed at least 80 nano-seconds before the DSP can properly access the memory. This results in an 80 percent reduction in the efficiency of memory access.
Conventional uses of digital signal processing systems include real time processing, which requires an enormous amount of processing power from a digital signal processing system. This is usually provided by an as-fast-as-possible DSP, which ideally uses memory that is as fast (or faster) than the DSP memory access cycle. A DSP system that meets these requirements is difficult and expensive to achieve, and is often limited by the fastest available memory.
The conventional solution to real time processing and other high power digital signal processing needs are the use of parallel DSP's, requiring a plurality of DSP's and therefore a multiplicity of high speed memory.